Method of preparing a synthetic resin varnish



Patented Oct. 8, 1929 UNITED STATES PATENT OFFICE QUSTAVE E. LANDT AND WILLIAM H. ADAMS, JR., OF NORRISTOWN, PENNSYLVANIA,

ASSIGNORS, BY MESNE ASSIGNMENTS, TO

CONTINENTAL-DIAMOND FIBRE COMPANY,

OF NEWARK, DELAWARE, A CORPORATION OF DELAWARE METHOD OF PREPARING A SYNTHETIC RESIN VARNISH No Drawing. Original application filed January 4, 1927, Serial No. 159,014. Divided and this application area August 31, 1927.

Our invention relates to a method of preparing a synthetic resin varnish and is a division of our application Serial No. 159,014, filed January 4, 1927 for Method of making hexame-thylenetetramine.

One object of our invention is to provide a process for the manufacture of a synthetic resin varnish by which hexamethylenetetramine is prepared in the organic solvent vehicle in which the initial condensation product-of the synthetic resin is dissolved, thereby obviating the necessity of separating the hexamethylenetetramine in a crystalline form and resulting also in a material saving in organic solvents.

At the present time, hexamethylenetetramine is prepared commercially by passing a stream of ammonia gas or a solution of ammonium hydroxide into a water solution of' formaldehyde whereupon ammonia and the formaldehyde react, liberating water and forming the hexamethylenetetramine. Hexamethylenetetramine is relatively soluble in water and therefore must be recovered by evaporation. In order that the hexamethylenetetramine may be in a purified crystalline form, it is redissolved in alcohol and recrystallized therefrom.

7 Our invention is characterized by the reaction of the formaldehyde and the ammonia in an organic solvent solution, thereby elimi nating two steps now used in plant practice, namely, the evaporation of the water from the original reaction products and the subsequent recrystallization of the hexamethylenetetramine from the alcohol. We preferably employ as the organic solvent ordinary commercial alcohol which, as is well known, contains 5% of water. This small amount of water which is present in commercial alcohol and the amount of water formed chemically during the process, is suiiicient to keep the hexamethylenetetramine to some extent in solution. The formaldehyde may bedisso lved in the alcohol and the gaseous ammonia passed therein or the process may be reversed by dissolving the ammonia in the alcohol and passing formaldehyde into it. A satisfactory method also results if both the formaldehyde and the ammonia are passed int the alcohol Serial No. 216,788.

six mols of the former react with 4 mols of the latter to form the compound. The reaction may be represented as follows:

For- Ammonia Hexameth- Water maldehyde ylenetetramine 1 Hence in the preparation of the compound according to the method here disclosed, the ratio of the two reacting components if they are to be passed simultaneously into the solution are kept approximately in this ratio.

However, if one of the components is dis-- solved in thesolvent, then the other is passed into the solution until the reaction is complete, whereupon more of the component in solution may be added and the process continued. The balancing of the ratio of the components is within the skill of one familiar with chemical preparations and will to some extent depend on the condition of operation, for example, at times in order to insure a complete reaction, it may beadvisable to have present an excess of one of the reacting substances.

The synthetig resin industry in the manufacture of synthetic resin varnishes uses large" qpllantities of alcohol in the preparation of t ese solutions. T o thissyntheticf resin solution' in alcohol often times crystalline hexamethylenetetramine is added, in order that a potentially reactive varnish will be formed by which term is meant one that can be converted by heat easily and quickly into a hard, infusible synthetic resin. By the useof the solution of hexamethylenetetramine herein described, the potentially reactive varnish can be prepared simply by adding the initial its accompanying loss of alcohol. This direct step therefore is of great value in this industry for the manufacturers of synthetic resin especially adapted for use with that type of varnishes may saturate the alcoholwhich is to be used as a solutioni-n the manufacture of the varnish with the hexamethylenetetra- -maldehyde and ammonia will react to form hexamethylenetetramine in the varnish itself thereby renderingit potentially reactive.

, While the above processesare a-p licable' for many types of synthetic resins, t ey are syntheticzresin known as phenolic conden sation products, that is tosay one in which a phenol is reacted with another compound such as formaldehyde, glycerine, furfural andthelike.

' Considerable modification in the propor- Q-Weclaim: I

' 1. A process for preparing a synthetic whereby a potentially reactive varnish is obtained.

resin varnish which comprises dissolvingl the v tions used and in the methods of carrying out the process are possible with no departure from the essential features of our invention.

resin varnish which. comprises dissolvin the mltial condensation productof a synt etic resin in an organic solvent, and thereafter reacting in said solution ammonia and formaldehyde to form henamethylenetetramine whereby a potentially reactive varnish is obtained.-

2. A process for preparing a synthetic' resin varnish which comprises dissolving the initial condensation product'of a phenolic resin in an organic solvent, and thereafter passing into said solution ammonia and formaldehyde to .form hexamethylenetetramine 3. A process for preparing a synthetic initial condensation product of a synt etic resinin alcohol, and thereafter reacting in said solution ammonia and formaldehyde-to form hexamethylenetetramine whereby a potentially reactive varnish is obtained.

resin in alcohol containing a little water, and thereafter reacting in said solution ammonia and formaldehyde to form hexamethylenetetramine whereby a potentially reactive varnish is obtained. a

GUSTAVE E. LANDT; WILLIAM H. ADAMS, JR.

4. A.process for preparing a synthetic v resin varnish which comprises dissolving'the initial condensation product of a phenolic resin in alcohol, and thereafterpassing into said solution ammonia and'formaldehyde to form hexamethylenetetramine whereby a potentially reactive varnish is obtained.

5. A process for preparing a, synthetic resin varnish which comprises dissolvin the initial condensation product of a syn etic 

